1. Field of the Invention
The present invention relates to packaging machines and to methods of packaging articles.
2. Description of the prior art
A previously proposed method of producing packs involved the steps of locating the intended contents of the packs in succession on a generally horizontally supported sheet of stretchable packaging material, clamping the sheet peripherally of each region of the sheet material which supports the intended contents, applying differential pressure to the region to stretch the sheet in the downward direction to accommodate the contents, and closing the pocket with a further sheet of material superimposed upon the first-mentioned sheet material and bonded thereto peripherally of the side region to form a said pack.
In the above method, the sheet is elastically stretched so that when released after being sealed, it contracts around the contents to produce a substantially flat pack. This method has the disadvantage that the elastic stretching of the sheet produces stresses in the parts of the sheet which are to be sealed so that during or immediately after sealing, these tensions tend to relieve themselves by crinkling the sheet and so there is a great danger of an imperfect seal being formed or the seal rupturing.